Fiber microphone

Abstract

A microphone, comprising at least two electrodes, spaced apart, configured to have a magnetic field within a space between the at least two electrodes; a conductive fiber, suspended between the at least two electrodes; in an air or fluid space subject to waves; wherein the conductive fiber has a radius and length such that a movement of at least a central portion of the conductive fiber approximates an oscillating movement of air or fluid surrounding the conductive fiber along an axis normal to the conductive fiber. An electrical signal is produced between two of the at least two electrodes, due to a movement of the conductive fiber within a magnetic field, due to viscous drag of the moving air or fluid surrounding the conductive fiber. The microphone may have a noise floor of less than 69 dBA using an amplifier having an input noise of 10 nV/√Hz.

What is claimed is: 
     
       1. A transducer comprising:
 a vibration-sensing conductive element suspended in a viscous medium subject to wave vibrations, the vibration-sensing conductive element being sufficiently thin and having a sufficient length to have at least one portion of the vibration-sensing conductive element that is induced by viscous drag with respect to the viscous medium to move corresponding to the wave vibrations of the viscous medium; and 
 a sensor configured to determine the movement of the at least one portion of the vibration-sensing conductive element over a frequency range comprising 100 Hz. 
 
     
     
       2. The transducer of  claim 1 , wherein the vibration-sensing conductive element comprises a fiber. 
     
     
       3. The transducer of  claim 1 , wherein the vibration-sensing conductive element comprises a ribbon. 
     
     
       4. The transducer of  claim 1 , wherein the vibration-sensing conductive element comprises a beam. 
     
     
       5. The transducer of  claim 1 , wherein the vibration-sensing conductive element comprises a plurality of parallel conductive fibers held in fixed position at respective ends of each of the plurality of conductive fibers. 
     
     
       6. The transducer of  claim 5 , wherein the plurality of parallel conductive fibers are wired in series. 
     
     
       7. The transducer of  claim 1 , wherein the sensor is sensitive to a movement of the vibration-sensing conductive element in a plane normal to a length axis of the vibration-sensing conductive element. 
     
     
       8. The transducer of  claim 1 , wherein the wave vibrations are acoustic waves and the sensor is configured to produce an audio spectrum output. 
     
     
       9. The transducer of  claim 1 , wherein the vibration-sensing conductive element is confined to a space within a wall having at least one aperture configured to pass the wave vibrations through the wall. 
     
     
       10. The transducer of  claim 1 , wherein:
 the vibration-sensing conductive element comprises a plurality of parallel conductive fibers; and 
 the sensor is configured to determine an average movement of the plurality of parallel conductive fibers in the viscous medium. 
 
     
     
       11. The transducer of  claim 1 , wherein the vibration-sensing conductive element comprises a plurality of fibers arranged in a spatial array, such that a sensor signal from a first of said plurality of fibers cancels a sensor signal from a second of said plurality of fibers under at least one state of wave vibrations of the viscous medium. 
     
     
       12. The transducer of  claim 1 , wherein:
 the vibration-sensing conductive element is disposed within a non-optical electromagnetic field; and 
 the non-optical electromagnetic field is dynamically controllable in dependence on a control signal. 
 
     
     
       13. The transducer of  claim 1 , wherein the vibration-sensing conductive element comprises spider silk. 
     
     
       14. The transducer of  claim 1 , wherein the vibration-sensing conductive element comprises a metal. 
     
     
       15. A transducer comprising:
 a ribbon suspended in a viscous medium subject to wave vibrations, the ribbon being sufficiently thin and having a sufficient length to have at least one portion of the ribbon that is induced by viscous drag with respect to the viscous medium to move corresponding to the wave vibrations of the viscous medium; and 
 a sensor configured to determine the movement of the at least one portion of the ribbon over a frequency range comprising 100 Hz. 
 
     
     
       16. The transducer of  claim 15 , wherein the sensor is sensitive to a movement of the ribbon in a plane normal to a length axis of the ribbon. 
     
     
       17. The transducer of  claim 15 , wherein the ribbon is confined to a space within a wall having at least one aperture configured to pass the wave vibrations through the wall. 
     
     
       18. The transducer of  claim 15 , wherein:
 the ribbon is disposed within a non-optical electromagnetic field; 
 the sensor is configured to determine the movement of the ribbon selectively dependent on an interaction of the ribbon with the non-optical electromagnetic field; and 
 the non-optical electromagnetic field is dynamically controllable in dependence on a control signal. 
 
     
     
       19. A method of sensing a wave in a viscous fluid, the method comprising:
 providing a space containing a viscous fluid subject to perturbation by waves; 
 providing at least one vibration-sensing conductive element, surrounded by the viscous fluid, having a thickness and length such that a movement of at least a portion of the vibration-sensing conductive element approximates the perturbation of the fluid surrounding the vibration-sensing conductive element by the waves along an axis normal to the vibration-sensing conductive element; and 
 transducing the movement of at least one vibration-sensing conductive element to an electrical signal. 
 
     
     
       20. The method of  claim 19 , wherein:
 the waves are acoustic waves within an audio spectrum; 
 the at least one vibration-sensing conductive element interacts with a magnetic field to induce a current dependent on the movement; and 
 the electrical signal corresponds to the acoustic waves.